> ## Documentation Index
> Fetch the complete documentation index at: https://calcs.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# Design a Cold-Formed Steel Beam to AS/NZS 4600:2018
> Design cold-formed steel beams to AS/NZS 4600:2018 using the Direct Strength Method, with a built-in database of Australian CFS sections.
Beam reactions link to the columns and footings below, so load changes propagate downstream automatically. Design cold-formed steel beams to AS/NZS 4600:2018 using the direct strength method. A built-in database of Australian CFS sections covers furrings, top hats, and custom shapes with live Finite Strip Method signature curves.
## Worked example
### Simple and Complex Beam Worked Examples
[How to Design a Cold Formed Steel Beam Using AS4600:2018 in Calcs.com](https://fast.wistia.com/embed/medias/dwc5eyfq2c) from [Calcs.com](https://clearcalcs.wistia.com/medias/dwc5eyfq2c).
## Method & scope
| Property | Detail |
| ---------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Design standards | AS/NZS 4600:2018 |
| Regions | Australia & New Zealand |
| Presets | Generic Beam, Rafter, Roof Bearer, Underpurlin, Strutting / Counter-Strutting Beam, Verandah Beam, Hanging Beam, Ceiling Joist, and 6 more |
| What it checks | Section moment capacity (AS/NZS 4600:2018, Cl. 3.3.2), Member buckling capacity (AS/NZS 4600:2018, Cl. 7.2.2), Shear capacity and web holes (AS/NZS 4600:2018, Cl. 7.2.3), Bearing capacity (AS/NZS 4600:2018, Cl. 3.3.6), Combined bending and shear (Cl. 7.2.3.5) and bending and bearing (Cl. 3.3.7), Deflection analysis (AS/NZS 4600:2018, Cl. 7.1.4) |
#### See the exact clause
Every check in this calculator links back to its governing clause in AS/NZS 4600:2018. Open the **Formula Reference** panel on any result and select the clause reference to read it. See [Viewing Clauses from Inside a Calculator](/docs/running-calculations/standards-and-codes/viewing-clauses-from-inside-calculator).
#### Calculation method
The Cold-Formed Steel Beam calculator designs CFS beams using the Direct Strength Method (DSM) per AS/NZS 4600:2018 Cl. 7. Rather than the traditional effective width method, DSM uses Finite Strip Method (FSM) analysis to calculate elastic buckling moments for all relevant modes, then applies DSM strength curves to determine design capacities.
##### Section moment capacity (AS/NZS 4600:2018, Cl. 3.3.2)
The section moment capacity phi\_b × M\_s is computed from the FSM-determined local and distortional buckling loads and the full cross-section yield moment M\_y. For back-to-back or boxed beam configurations, section capacity is doubled.
*utilization = M* / (phi × M\_s) ≤ 1.0\*
##### Member buckling capacity (AS/NZS 4600:2018, Cl. 7.2.2)
Three member buckling checks are performed separately using the DSM interaction curves:
* **Global (lateral-torsional) buckling** (Cl. 7.2.2.1): capacity phi × M\_b,glob from FSM global buckling load, accounting for unbraced length and moment gradient
* **Local buckling** (Cl. 7.2.2.2): capacity phi × M\_b,local based on interaction between local and global modes
* **Distortional buckling** (Cl. 7.2.2.3): capacity phi × M\_b,dist based on the distortional buckling load from the FSM signature curve
Positive and negative moment member capacities are checked separately. The governing check uses the lowest capacity.
*utilization = M*+gov / (phi × M\_b,gov+) ≤ 1.0\*
*utilization = M*-gov / (phi × M\_b,gov-) ≤ 1.0\*
##### Shear capacity and web holes (AS/NZS 4600:2018, Cl. 7.2.3)
Shear capacity phi × V\_v is checked at the critical section. If web holes are present (depth d\_wh, spacing s\_wh), a reduced shear capacity phi × q\_s × V\_v is also checked at the hole locations. No web holes are permitted within bearing lengths.
*utilization = V* / (phi × V\_v) ≤ 1.0\*
##### Bearing capacity (AS/NZS 4600:2018, Cl. 3.3.6)
Bearing (web crippling) capacity phi × R\_b is checked for reactions at supports and concentrated loads, based on section type and bearing length. Bearing is only checked for standard Cee or Zed sections bent about the X-X axis.
##### Combined bending and shear (Cl. 7.2.3.5) and bending and bearing (Cl. 3.3.7)
Interaction checks are performed where both effects are significant:
**utilization (MV) = combined interaction ratio ≤ 1.0**
**utilization (MR) = combined interaction ratio ≤ 1.0**
##### Deflection analysis (AS/NZS 4600:2018, Cl. 7.1.4)
Deflections use an effective second moment of area I\_eff that accounts for local and distortional buckling under service loads. Short-term, long-term, and imposed-load deflections are each checked against span/limit criteria.
## How to use it
Open it from **Run calc** in the About this calculator panel above. To start from a typical setup, choose one of the presets listed there.
Work through the input sections from top to bottom. Click any input label to see its reference explanation, clause, conditions and assumptions. See [Checks, References, Conditions and Assumptions](/docs/running-calculations/checking-results/checks-references-conditions-assumptions).
Check the utilization of each governing check in the summary, then export a PDF report. See [Views and Export](/docs/running-calculations/exporting-reports/views-and-export).
## Available presets
Each preset opens the calculator with a typical setup already entered.
| Preset | Open in Calcs.com |
| ------------------------------------------------------------- | --------------------------------------------------------------------------------------------------- |
| Generic Beam | [Run with preset](https://app.calcs.com/new/sheet/cfsSteelBeamAS4600-2018?presetCode=genericBeam) |
| Rafter | [Run with preset](https://app.calcs.com/new/sheet/cfsSteelBeamAS4600-2018?presetCode=rafter) |
| Roof Bearer | [Run with preset](https://app.calcs.com/new/sheet/cfsSteelBeamAS4600-2018?presetCode=roofBearer) |
| Underpurlin | [Run with preset](https://app.calcs.com/new/sheet/cfsSteelBeamAS4600-2018?presetCode=underpurlin) |
| Strutting / Counter-Strutting Beam | [Run with preset](https://app.calcs.com/new/sheet/cfsSteelBeamAS4600-2018?presetCode=struttingBeam) |
| Verandah Beam | [Run with preset](https://app.calcs.com/new/sheet/cfsSteelBeamAS4600-2018?presetCode=verandahBeam) |
| Hanging Beam | [Run with preset](https://app.calcs.com/new/sheet/cfsSteelBeamAS4600-2018?presetCode=hangingBeam) |
| Ceiling Joist | [Run with preset](https://app.calcs.com/new/sheet/cfsSteelBeamAS4600-2018?presetCode=ceilingJoist) |
| Roof Lintel | [Run with preset](https://app.calcs.com/new/sheet/cfsSteelBeamAS4600-2018?presetCode=roofLintel) |
| Wind Beam | [Run with preset](https://app.calcs.com/new/sheet/cfsSteelBeamAS4600-2018?presetCode=windBeam) |
| Floor Joist | [Run with preset](https://app.calcs.com/new/sheet/cfsSteelBeamAS4600-2018?presetCode=floorJoist) |
| Floor Bearer | [Run with preset](https://app.calcs.com/new/sheet/cfsSteelBeamAS4600-2018?presetCode=floorBearer) |
| Floor Lintel | [Run with preset](https://app.calcs.com/new/sheet/cfsSteelBeamAS4600-2018?presetCode=floorLintel) |
| Retaining Wall Sleeper | [Run with preset](https://app.calcs.com/new/sheet/cfsSteelBeamAS4600-2018?presetCode=RWsleeper) |
## Common questions
The calculator applies the Direct Strength Method (DSM) per AS/NZS 4600:2018, Cold-formed steel structures. DSM uses Finite Strip Method (FSM) analysis to determine elastic buckling loads for local, distortional, and global buckling modes, then calculates design capacities using the DSM strength curves. This replaces the traditional effective width method for sections in the database.
Key inputs are span length, support conditions, steel section (from the built-in Australian CFS database or custom dimensions), steel grade (G250, G300, G450, G550), and applied loads (distributed, point, or line loads). For custom sections, you enter cross-section dimensions and the calculator generates FSM signature curves automatically.
Checks include bending capacity (local, distortional, and global lateral-torsional buckling), shear capacity, and deflection against serviceability limits. The FSM signature curves showing elastic buckling moments versus half-wavelength are displayed so you can verify the governing buckling mode. Utilization ratios and code clause references are shown for every check.
The built-in database includes C-sections (lipped and unlipped), Z-sections, top hat sections, furring channels, and angle sections commonly used in Australian construction. Custom open and closed section geometries can be defined manually. Hollow sections (RHS, SHS) that are not cold-formed are handled by the separate Steel Beam (AS 4100:2020) calculator.
Beam support reactions link directly to column and footing calculators in the same Calcs.com project. For CFS framing systems where a beam reaction feeds into a CFS column or a concrete pad footing, changes to span or loading update all downstream calculations automatically, no manual transfer of reaction values between templates.
## Next steps
Design steel beams to AS 4100:2020 with multiple supports and loads. Floor- and roof-beam presets cut repetitive entry.
Design steel lintels supporting masonry, as an angle, a T-lintel, or a PFC with plate, to AS 4100:2020.
Design cold-formed steel members to AS/NZS 4600:2018 by the Direct Strength Method. Input analysis forces to check moment, shear, bearing, and combined actions.
